Immunogenicity of adalimumab reference product and adalimumab-adbm in patients with rheumatoid arthritis, Crohn's disease and chronic plaque psoriasis: a pooled analysis of the VOLTAIRE trials.

Objective: This post hoc analysis compared the immunogenicity of the biosimilar adalimumab-adbm (Cyltezo) with the adalimumab reference product (RP; Humira) across indications, including rheumatoid arthritis (RA), Crohn's disease (CD) and plaque psoriasis (PsO), and by patient sex in the VOLTAIRE trials programme.

Methods: In each active-comparator randomised controlled trial (RCT), immunogenicity was assessed at various time points by the proportion of patients with antidrug antibodies (ADAs) and neutralising antibodies (nAbs), using acid dissociation followed by electrochemiluminescence assay. Assay sensitivity was 50 ng/mL, and drug tolerance was ≥30 µg/mL (free drug) at the low positive control level.

Results: Minor differences in immunogenicity parameters (ADAs, ADA titres and nAbs) were evident between adalimumab-adbm and adalimumab RP across these three immune-mediated inflammatory diseases (IMIDs). The proportion of ADA-positive and nAb-positive patients increased from baseline over time in all three RCTs, as expected, and was similar in the RA and CD RCTs but with higher numbers of ADA-positive and nAb-positive patients reported in the PsO trial. Subgroup analysis by patient sex showed the same trend.

Conclusions: Differences among the RCTs may partially be explained by concomitant background therapy (methotrexate) in the RA trial, stable doses of azathioprine, 6-mercaptopurine or methotrexate in 36% of patients with CD and absence of background therapy in the PsO RCT. The analyses further confirm the biosimilarity of adalimumab-adbm with the adalimumab RP across IMIDs and provide supporting evidence that adalimumab-adbm is an interchangeable biosimilar with consistent clinical results in patients originally treated with the RP.

Trial registration numbers: VOLTAIRE-RA (NCT02137226; EudraCT 2012-002945-40); VOLTAIRE-CD (NCT02871635; EudraCT 2016-000612-14); VOLTAIRE-PsO (NCT02850965; EudraCT 2016-000613-79).